In ruminants, e.g., beef and dairy cattle, sheep, etc., ingested feed first passes into the rumen, where it is pre-digested by fermentation. During this period of fermentation the ingested feed is subjected to rumination, which is part of a digestive process involving regurgitation. After a period of fermentation, adsorption of digested mutrients starts and continues in the subsequent sections of the digestive tract. This digestive process is described in detail by D. C. Church, "Digestive Physiology and Nutrition of Ruminants," Vol. 1, O.S.U. Book Stores, Inc., of Corvallis, Oreg.
The rumen serves as an important location of metabolic breakdown of ingested foodstuffs through the action of microorganisms which are present therein. Ingested food is typically retained in the rumen for from about 6 to about 30 hours, during which time it is subject to metabolic breakdown by the rumen microorganisms. Much ingested protein material is broken down in the rumen to soluble peptides and amino acids and utilized by the rumen microorganisms. When the rumen contents pass into the abomasum and intestine, the microbial mass is digested, thus providing protein to the ruminant. Thus, the natural nutritional balance of the ruminant animal is primarily a function of the microbial composition and population.
In preparing nutrients and medicaments intended for administration to ruminants, it is important to protect the active ingredients against the environmental conditions of the rumen, i.e., microbial degradation and the effects of a pH in the range of about 5.5 to about 7.0, so the active substance will be saved until it reaches the particular location where adsorption takes place. It is well known that the rate of meat, wool and/or milk production can be increased if sources of growth limiting essential amino acids, and/or medicaments, are protected from alteration by microorganisms residing in the rumen and become available for direct adsorption by the animal later in the gastrointestinal tract.
Materials which protect the core against degradation by the rumen contents should be resistant to attack by the rumen fluid which contains enzymes or microorganisms but must make the active ingredient available rapidly in the more acidic fluid of the abomasum at a pH within the normal physiological range of about 2 to about 3.5.
Because proteins are subject to breakdown in the rumen, it has been suggested that protein-containing nutrients fed to ruminants be treated so as to permit passage without microbial breakdown through the rumen to the abomasum. Suggested procedures have included coating the protein materal, for example, with fats and vegetable oils; heat treating of the protein material; reacting the protein material with various compounds such as formaldehyde, acetylenic esters, polymerized unsaturated carboxylic acid or anhydrides and phosphonitrilic halides, etc.
It is well known that all proteins found in animal and plant life are chemical compounds containing different combinations of over 20 amino acids, the number and arrangement of such acids being fixed in any particular protein. Twelve of these amino acids can be synthesized in nutritionally adequate amounts from other substances by biochemical processes normally present in most animals, but the remaining 10 amino acids are not synthesized in sufficient quantities and must be ingested by the animal. Since the proportions of the constituent amino acids in a particular protein cannot be varied, the essential amino acid least in supply limits the amount of that protein which can be produced by the animal. Consequently, for any given diet, there will be a particular essential amino acid which limits the production of protein incorporating that essential amino acid unless, of course, two or more such amino acids are equally limiting.
It is likewise well-known that medicaments are more effective when they are protected from the environment of the rumen. See, for example, U.S. Pat. Nos. 3,041,243 and 3,697,640.
In accordance with the present invention, a polymeric coating having a hydrophobic substance and a flake material dispersed therein, which is resistant to environmental conditions of the rumen but releases the core material under the environmental conditions of the abomasum (postruminal), provides a very desirable utilization efficiency by ruminants. The core material may also contain a neutralizer to provide a pH above about 5.5.
The coating material has the ability to withstand environmental conditions of the rumen, and the ability to expose the core material of the pellet in the environment of the abomasum. Thus, the coating material is resistant to pH conditions of about 5.5 for at least about 24 hours. The coating material releases the core material upon exposure to postruminal environmental conditions having a pH of about 3.5 after a time of about 10 minutes to about 6 hours. The exposure of the core may occur by the coating becoming permeable to the fluids therein or by dissolving or disintegrating. Another requirement for the coating material is to have the ability to withstand storage conditions of relatively high heat and/or humidity without a significant amount of blocking.
U.S. Patents of interest include Nos. 3,619,200; 3,880,990; 3,041,243; 3,697,640; 3,988,480; 3,383,283; 3,275,518; 3,623,997; 3,073,748; 3,829,564; 3,832;252; 3,917,813.
U.S. Pat. No. 4,181,708, incorporated herein by reference, discloses coatings comprising a polymer, hydrophobic substance and flake material, but does not disclose treatment of the flake material.
Also, U.S. Pat. Nos. 4,177,255; 4,196,187; 4,181,709 and 4,181,710 are of interest.